서울대학교 중앙도서관
S-Space 소개
My S-Space
로그인이 필요합니다.
Login

S-Space

Publications

Detailed Information

Observation of Energy and Baseline Dependent Reactor Neutrino Disappearance in the RENO Experiment

DC Field Value Language
dc.contributor.advisor김수봉-
dc.contributor.author최원국-
dc.date.accessioned2017-07-19T06:11:00Z-
dc.date.available2017-07-19T06:11:00Z-
dc.date.issued2016-02-
dc.identifier.other000000133503-
dc.identifier.urihttp://dcollection.snu.ac.kr:80/jsp/common/DcLoOrgPer.jsp?sItemId=000000133503-
dc.description학위논문(박사)--서울대학교 대학원 :자연과학대학 물리·천문학부,2016. 2. 김수봉.-
dc.description.abstractThe Reactor Experiment for Neutrino Oscillation (RENO) began gathering data in August, 2011. The RENO is designed to measure the
neutrino mixing angle Theta 13 and mass squared di fference		-
dc.description.abstractDelta m^2_ee-
dc.description.abstractwhich is
the electron neutrino weighted average mass square di fference		-
dc.description.abstractDelta m^2_31-
dc.description.abstractand-
dc.description.abstractDelta m^2_32-
dc.description.abstract.
The experimental site of RENO is the Hanbit nuclear power plant,
which is 280 km away from the capital city of Koera, Seoul. There
are 6 reactors in the Hanbit nuclear power plant, equally spaced in
a single line. The Experiment used two identical detectors. The near
detector (far detector) is located at 294 m (1384 m) from the cen-
ter of this six reactor array. and the flux-weighted average distance
between the reactors and the far (near) detector is 408.6 m (1444.0
m). The experimental has analyzed about 500 live days of data in
the period between August 2011 and January 2013. In this period,
the far (near) detector observed 31541 (290775) electron antineu-
trino candidate events with a background fraction of 4.9% (2.8%).
The measured prompt spectra has an excess of reactor e of approx-
imately 5 MeV relative to the prediction from the most commonly
used model. The excess is proportional to reactor thermal output
power, therefore the excess is the neutrino signal coming from reac-
tor cores and not a background. To aviod this problem, the data are
analysed based on the measured far-to-near ratio of prompt spectra.
A clear energy and baseline dependent disappearance of reactor e is
observed in the de cit of the observed amount of e. From this de cit,
we can determine sin^2 2theta_13 = 0.082 +- 0.009(stat.) +- 0.006(syst.) and		-
dc.description.abstractDelta m^2_ee-
dc.description.abstract= 2.62+0.21-0.23(stat.) +0.12 - 0.13(syst.) (X10^-3eV^2) based on a rate and spectra analysis. The precise measurement of Theta_ 13 would be a important milestone in determination of the leptonic CP phase if combined
with a result of an accelerator neutrino beam experiment.		-
dc.description.tableofcontentsChapter 1 Introduction 1
1.1 Overview of Neutrino Oscillation 1
1.2 Neutrino Oscillation 2
1.3 Reactor Neutrino Experiment 3
1.3.1 Production of Reactor Neutrino 4
1.3.2 Detection of Reactor Neutrino 6
1.3.3 Neutrino Oscillation in Reactor Experiments 8
1.3.4 Determination of Mixing Angle Theta_ 13 10
1.3.5 Determination of Mass Squared Di fference |Delta m^2_ee| 10
1.4 The RENO Experiment 12

Chapter 2 RENO Experimental Arrangement and Detector 13
2.1 Overview 13
2.2 Experimental Arrangement 15
2.2.1 Near and Far Detectors 15
2.2.2 Hanbit Nuclear Power Plant 16
2.2.3 Underground Facility and Experiment Halls 18
2.3 Detector Components 18
2.3.1 Target and Gamma Catcher 20
2.3.2 Bu er 22
2.3.3 Veto 23
2.3.4 PMT 24
2.4 Liquid Scintillator 28
2.4.1 Optimization for Liquid Scintillator 29
2.4.2 Gd-loaded liquid scintillator 31
2.5 Data Acquisition (DAQ) and Monitoring System 34
2.5.1 Electronics 34
2.5.2 Data taking flow 36
2.5.3 Monitoring System 39

Chapter 3 Expected Flux and Spectrum of Reactor Neutrino 45
3.1 Reactor Neutrino Production 45
3.2 Calculation of the Flux and the Spectrum 49
3.2.1 Calculation of Expected Antineutrino Flux 49
3.2.2 Expected Interaction Antineutrino Spectrum 53
3.3 Systematic Uncertainties of Expected Flux and Spectrum 55

Chapter 4 Energy Calibration 59
4.1 Energy Calibration System 59
4.2 Energy Reconstruction 61
4.3 Radioactive sources 62
4.4 Energy Conversion Function 64
4.5 Energy Resolution 68

Chapter 5 Monte Carlo Simulation 71
5.1 Detector Simulation 71
5.1.1 Software Tools 73
5.1.2 Optical Photon Processes 74
5.1.3 Quenching at low energy 77
5.2 Energy Calibration of Monte Carlo 79
5.2.1 Energy Conversion Function for Monte-Carlo 79
5.2.2 Correction of Energy Resolution for MC Prompt Energy Spectrum 81
5.2.3 MC prompt energy spectrum 83

Chapter 6 Data Sample and Event Selection for IBD Candidates 85
6.1 Data Sample 85
6.2 Backgrounds 88
6.2.1 Accidental Background 88
6.2.2 Fast Neutron Background 88
6.2.3 9Li/8He 89
6.2.4 Backgrounds from 252Cf contamination 90
6.3 Removal of Gamma-Rays from Radioactivity, Noise and Flashers 91
6.3.1 Removal of Gamma-Rays from Radioactivity and Noise 91
6.3.2 Removal of Flasher 92
6.4 Removal of Accidental Backgrounds 96
6.4.1 Radioactive Backgrounds 96
6.4.2 Removal of Accidental Backgrounds 98
6.5 Removal of Background associated with cosmic-rays 104
6.6 Removal of Fast Neutron Backgrounds 107
6.6.1 Any Trigger Veto Cut 107
6.6.2 Bu er Trigger Veto Cut 108
6.6.3 Prompt-like Trigger Veto Cut 110
6.7 Removal of 252Cf contamination 111
6.7.1 Time Correlated Veto Cut 112
6.7.2 Spatial Correlated Veto Cut 115
6.7.3 Time and Spatial Correlated Veto Cut 118
6.8 Signal Loss from IBD Selection 121
6.8.1 Signal Loss from Time Coincidence 121
6.8.2 Signal Loss from Energy Threshold 122
6.8.3 Signal Loss from Spatial Correlation and Removal of Gamma-Rays from Radioactivity and Flashers 122
6.8.4 Signal Loss from Timing Veto with Muon or Trigger Information 122
6.8.5 Signal Loss from Cf Removal 122
6.9 Summary 123

Chapter 7 Background Estimation 125
7.1 Accidental 125
7.2 Fast Neutron 127
7.3 9Li / 8He 129
7.4 Backgrounds due to 252Cf Contamination 131
7.5 Summary 133
7.5.1 Summary for Data Set A 133
7.5.2 Summary for Data Set B 134
7.5.3 Summary for Data Set A+B 134

Chapter 8 Systematic Uncertainty 135
8.1 Detector E ciency 135
8.1.1 E ciency from IBD selection 135
8.1.2 Detection e ciency 136
8.2 Detector Related Uncertainty 138
8.2.1 Common Systematic Uncertainties Related with Detector 138
8.2.2 Uncommon Systematic uncertainties from IBD Selection 140
8.3 Reactor Related Uncertainty 141
8.4 Energy Scale Uncertainty 142
8.5 Background Uncertainty 144

Chapter 9 Measurement Results of Theta_13 and |Delta m^2_ee| 147
9.1 Observed IBD Candidate and Backgrounds 147
9.2 Expected Neutrino Oscillation Templates 151
9.2.1 Expected IBD Prompt Spectrum 151
9.2.2 5 MeV Excess 152
9.2.3 Oscillation Templates 154
9.3 Systematic Uncertainties 155
9.3.1 Uncertainties of Detection E ciency 155
9.3.2 Reactor Related Uncertainties 155
9.3.3 Energy Scale Uncertainties 155
9.3.4 Background Uncertainties 156
9.4 Rate Only Analysis 156
9.4.1 2 Fitting of Rate Only Analysis 156
9.4.2 Fit Result of Rate Only Analysis 158
9.5 Rate + Shape Analysis 159
9.5.1 2 Fitting of Rate + Shape Analysis 159
9.5.2 Fit Result of Rate + Shape Analysis 162
9.6 Shape Only Analysis 163
9.6.1 2 Fitting of Shape Only Analysis 163
9.6.2 Fit Result of Shape Only Analysis 163
9.7 Summary and Comparison of Experimental Results 164
9.7.1 Results Summary 164
9.7.2 Comparison of Experimental Results 166

Chapter 10 Summary and Discussion 169


Appendix 173
Appendix A PMT Charge Stability 173
Appendix B Signal Loss from IBD Selection Criteria 181
Appendix C Study of Fast Neutron Background Shape 191
Appendix D Study of 9Li/8He Background Shape 193
Appendix E Study of 252Cf Background Shape 201
Appendix F Estimation of Baseline between Reactors and Detectors 209
Appendix G Optimization of MC Parameter 213
Appendix H Measurement of Birks Constant 221

Bibliography 227

국문초록 231		-
dc.format.extent230-
dc.language.isoeng-
dc.publisher서울대학교 대학원-
dc.subject중성미자, Neutrino, Oscillation, theta13-
dc.subject.ddc523-
dc.titleObservation of Energy and Baseline Dependent Reactor Neutrino Disappearance in the RENO Experiment-
dc.typeThesis-
dc.typeDissertation-
dc.contributor.AlternativeAuthorWonqook Choi-
dc.contributor.department자연과학대학 물리·천문학부-
dc.description.degreeDoctor-
dc.date.awarded2016-02-
dc.contributor.major입자물리실험-
dc.identifier.holdings000000000027▲000000000027▲000000133503▲-
Appears in Collections:
Files in This Item:

Altmetrics

Item View & Download Count

Show Simple Item Record
Find it @ SNU

  • mendeley

Items in S-Space are protected by copyright, with all rights reserved, unless otherwise indicated.

Share

qrcode
SNS Share